Head Injury Criterion (“HIC”) is a measure of the likelihood of head injury resulting from an impact. The HIC is used to assess safety related to occupants. Normally, this variable is derived from the acceleration/time history of an accelerometer mounted at the center of gravity of a dummy's head when the dummy is exposed to crash forces. As a result, HIC includes the effects of head acceleration and the duration of the acceleration (i.e., large accelerations may be tolerated if the duration is very short). Another test criterion is delethalization, which includes requirements that limit the exposure of sharp edges to occupants. During a crash event, sharp edges may occur as a result of head impact.
In various modes of transportation, many passenger seats are placed behind other passenger seats. These passenger seats may be designed with a variety of comforts for passengers seated thereon, including communication and entertainment features, such as video monitors, telephones, shrouds, or other items. For convenience and individual comfort, the video monitors are typically mounted in the line of sight of the occupants, usually behind the headrest of the forward seat. During a minor crash landing, a passenger may be thrown forward so that the passenger's head and/or body strikes these structures due to inertial loads from the event.
Therefore, the addition of video monitors in passenger seatbacks may pose a challenge to occupant safety since impact testing must show allowable HIC according to FCC regulations. Furthermore, the video monitor display may delaminate upon impact, which may create sharp edges and also pose a challenge to occupant safety since impact testing must also show allowable delethalization according to FCC regulations.
Conventionally, energy dissipation solutions focused on allowing the passenger seatback to pivot forward in a controlled manner via features located in the lower back area of the passenger seatback that give way under a certain load. Generally, these features include metallic brackets with a designed shear area or shear bolts that are attached to the back diaphragm of the seat. There are, however, limitations on the adjustability of the load under which these features are designed to give way.
As a result, it may be desirable to integrate monitors into passenger seatback that have energy dissipation features included at the location of the monitor installation, which will allow for energy dissipation within allowable HIC values and prevents monitor display screen delamination.